1. Field of the Invention
This invention relates generally to sludge collection apparatus and more specifically to wear shoes and guide lugs attached to the sludge collection flights for guided sliding movement of the flight along the elevated return rails of the sludge collector.
2. Description of the Prior Art
Sludge collection apparatus, of the nature of the present invention, generally includes molded plastic beams or flights, horizontally disposed and extending laterally across a sludge collection unit or cell forming a portion of a larger sludge tank having many such units disposed side by side in fluid communication. The flights of each unit are connected to an endless chain which is driven by a sprocket to drag the flights adjacent the bottom of each unit, to transport the settled sludge to one end of the unit for further treatment. At the end of travel of the flight adjacent the tank bottom, the chain and attached flights are guided to a return path along horizontal elevated rails.
The individual sludge collecting units, in their side by side relationship, are separated, adjacent the bottom, by short partitions therebetween running parallel with the direction of travel of the flights. Otherwise, the units are generally open for fluid communication between all the units of a single tank. The tank is generally fabricated of concrete, and therefore, rails are disposed in the floor providing a slight elevated ridge above the floor on which the flight can ride. The flights have attached thereto replaceable planar faced wear shoes secured in alignment with the floor rails to accept, on a easily removable and replaceable part, the wear caused by the sliding engagement. Also, the flights extend laterally so that the ends are generally adjacent the partition or sidewall of the unit which maintains the flight against excessive lateral movement, so that, within such permitted movement, the shoes and rails remain in engagement.
The flight also has attached to the opposite planar face a pair of replaceable wear shoes for protecting such opposite face of the flight against wear when it is being transported on the elevated return rails as the flights are dragged along their horizontal path back above the floor of the unit. However, as the return rails are above the partitions separating the unit, there are no sidewalls or partitions to maintain the flights against lateral movement. Thus, without lateral restraint, the return wear shoes and return rails could become misaligned causing wear on the flight itself; but, more critical, this misalignment may cause the flight to come into abutment with upper, intermittent rail support structure, causing the flight to become fractured or destroyed. Thus, it has been common practice to provide a lip extending below the planar wear surface of the return wear shoe for abutting engagement by the return rail to guide the flight on the return path against such excessive lateral movement. Heretofore, such lip was made as an integral unitary part of the wear shoe, such that the upper or return wear shoe could not be used as a bottom or floor wear shoe because the lip would engage and interfere with the bottom of the unit. Thus, the upper wear shoes were not interchangeable with the lower wear shoes.